Debt (Details) (USD $) In Thousands, unless otherwise specified	Apr. 30, 2013	Jan. 31, 2013
Summary of debt and its components
Total	$ 410,042	$ 410,042
2016 Tranche B term loans: due March 10, 2016, three-month LIBOR plus 4.00% with a 1.00% LIBOR floor [Member]
Summary of debt and its components
Total	117,399	117,399
2016 Extended term loans: due March 10, 2016, three-month LIBOR plus 4.00% [Member]
Summary of debt and its components
Total	191,101	191,101
Senior Subordinated Notes: due March 15, 2016, 10.375% [Member]
Summary of debt and its components
Total	$ 101,542	$ 101,542